Cutting bit



Sept. 29, 1942. H M, MORROW 2,297,362

CUTTING BIT Filed 001:. 3, 1940 fie. 4 25 22 /7a. 5 fia 20 INVENTOR.

BY Weir/1% 4402,2022

wwww m Patented Sept. 29, 1942 UNITED STATES PATENT OFFICE CUTTING BIT Harry M. Morrow, Canton, Ohio, assignor to The Bowdil Company 7 Application October 3, 1940, Serial No. 359,507

4 Claims.

My invention relates in general to cutting bits and more particularly to bits for cutting coal or other substances.

In the mining of coal or other substances, a cleft is cut in the lower level of the vein by means of a cutter bar around which revolves a power driven endless chain carrying a plurality of staggeredly arranged cutting bits constituting the subject matter of this invention. The shelf formed by the cleft is subsequently broken oft by means of explosives or other suitable methods. When cutting the cleft, in the interest of economy and the saving of power, it is highly desirable that the cutting bits be not only strong and durable but also eflicient in operation and free from drag.

An object of my invention is the provision of a cutting bit which requires a minimum amount of power to operate.

Another object of my invention is the provision of a cutting bit which produces very little drag.

Another object of my invention is the provision of a cutting bit which has a greater cutting clearance as the bit wears away.

Another object of my invention is to make the cutting clearance of the bit increase in substantial proportion to the amount that the cutting points of the bit wear away.

Another object of my invention is to make my bit have relatively narrow cutting faces for a substantial distance to give longer wear.

Another object of my invention is the provision of a cutting bit which is durable and adapted to out through hard substances.

Another object of my invention is the'provision of a plural-ended bit having a central body portion and a plurality of cutting portions extending radially therefrom in which the cutting portions have a greater cutting clearance as the cutting portions wear away.

Other objects and a fuller understanding of my invention may be had by referring to the following description and claims, taken in conjunction with the accompanying drawing, in which:

Figure 1 shows a rear elevational view of my new and improved cutting bit;

Figure 2 shows a side elevational View of my new and improved cutting bit as shown in Figure 1;

Figure 3 shows a front elevational View of my new and improved cutting bit as shown in Figure 1;

Figure 4 shows an enlarged cross-sectional view of my bit, taken along the line 4-4 of Figure 2;

Figure 5 shows an enlarged cross-sectional view of my bit, taken along the line 5 5of Figure 2;

Figure 6 shows an enlarged cross-sectional view of my bit, taken along the line 6.-6 of Figure 2; and

Figure 7 shows a cross-sectional view taken along the line 'I1 of Figure 1.

With reference to the drawing, my improved cutting bit is solid and may be made of steel, shaped by forging or in any other suitable fashion. In front elevation, the cutting face IO, of my bit is substantially triangular and has arrelatively large central body portion II and three relatively narrow cutting portions I2, I3 and I4 extending radially therefrom at approximately degrees apart. The cuttingportions J2, I3 and llllare substantially identical and thus the following description for the cutting portion I2 applies equally well for the other two. The contour of the side edges I5 and I6 for the front cutting face of the cutting portion I2 are depressed, arcuatey-or concaved, and form a cutting point I! at the outer end thereof. -The same applies to the cutting portions I3 and I4, in which the depressed, arcuate, or concaved'side edges thereof form cutting points I8 and I9,

The side clearance faces 20 and 2| for the cutting portion I2 converge toward the rear edges thereof and meet in a relatively sharp juncture 22 which curves in a radial direction between the central body portion I I and the cutting point H, see Figure 2. The side clearance faces 20 to 2| between the central body portion II and the cutting point I! are depressed, arcuate, or concaved to produce a greater cutting clearance as the cutting points wear away.

The bits are removably mounted in the lugs of the endless power driven chain which revolves around the cutter bar. Upon being mounted in the chain lugs, only one cutting portion is exposed for cutting operation. The other two cutting portions and the central body portion are clamped in the chain lug. When one of the cutting points of the bit wears away the bit is repositioned to expose another cutting portion for cutting operation, giving a triple cutting life to the bit. The cutting points may be treated or hardened by any suitable means such as, for example, by depositing a hardened metal thereon. The bits are held in the chain lugs at a slight forward angle as shown in Figure 2.

The provision of the varying cutting clearance is progressively shown in Figures 4, 5, and 6. In the region near the cutting points shown by Figure 4, the clearance is rather small. At the cutting points of the bit, the drag does not have an opportunity to manifest itself since th horizontal distance of the side walls across the bit in the rear of the cutting faces is small, and for this reason the cutting clearance in the region of the cutting points may be rather small without producing any substantial increase in the drag of the bits in the cutting operation. By making only a very small clearance in the region of the cutting points, the cross-sectional area of the cutting points may be kept at a maximum,

thereby giving additional strength to the cuttingpoints which are subjected to a great deal of strain during the cutting operation. As the cuttingpoints wear away, the horizontal distance Of the side clearance faces 20 and 2| of the bit-in rear of the cutting face increases, and for this reason an additional side clearance face drag would tend to be produced. In order to reduce this drag of the side clearance faces becauseof the additional cutting side wall depth of the bit, I provide for making the side clearance faces 20 and 2| of the bit depressed, arcuate or concaved, so that a greater clearance is produced a the cutting points of the bits wear away. The-cutting clearance is indicated by the reference character 23 and the increase in cutting clearance is illustrated by the increased lateral space upon opposite sides of the cross-sectional views of Figures 5 and 6 over Figure 4, taken at different horizontal cutting sections through the bits. Therefore, with my improved cutting bit the drag is kept at a low minimum, regardless of the amount of Wear that might occur upon the bits. Another result growing out of the depressed, arcuate, or concaved side clearance faces 20 and 2| of my cutting bit is the fact that the cutting faces remain relatively narrow for a considerable distance and do not begin to broaden until the side clearance faces 20 and 2| approach the central body portion II of the bit. Moreover, the clearance is proportionately distributed throughout the entire life of the bit, so that the drag is always maintained at a low minimum value.

The cutting portions l2, l3, and I4 are well anchored to the central body portion H by Web portion 24, 25, and 26 which give lateral support against a cutting force acting upon the cutting points, see the web portion 24 and 26 in Figure 7. The radial juncture 22 of the cutting portions extend from the points of the bit to the center thereof, see Figure 1. This construction provides strength to the bit against a front cutting force acting on the cutting points of the bit.

Although I have described my invention with a certain degree of particularity, it is understood that the present disclosure has been mad only byway of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention as hereinafter claimed.

I claim as my invention:

1. A multiple bit for cutter chains comprising a solid piece of metal having a central body portion and a plurality of radially disposed spacedapart cutting points with cutting edges extending between'said points, the'contour of the said cutting edges between the said cutting points and the central body portion being concave, one side of said multiple bit being approximately fiat and the other side being provided with radial ribs eX- tending to said points, each rib having a spacedapart pair of angularly disposed side clearance faces, one pair individual to each rib each of said side clearance faces being concaved and producing a greater cutting clearance as the cutting points wear away.

2. A triple-ended bit comprising a solid piece of metal having a central body portion and three cutting portions extending radially therefrom, at approximately degrees apart, each of said radially extending cutting portions having a cutting point and having a front cutting face and side clearance faces, the contour of the side edges of each of the front cutting faces between the central body portion and the cutting points being concaved, the side clearance faces of each of said radially extending cutting portions converging toward the rear edges thereof and meeting in a relatively sharp juncture, said juncture being curved. in a radial direction and extending between the central body portion and each of the cutting points, the front edges of the said side clearance faces meeting with the side edges of the front cutting faces, the said side clearance faces between the central body and the cutting points being concaved and producing a greater cutting clearance as the cutting points wear away.

3. A triple-ended bit comprising a solid piece of metal having a central body portion and three cutting portions extending radially therefrom, at approximately 120 degrees apart, each of said radially extending cutting portions having a cutting point and having a front cutting face and side clearance faces, the contour of the side edges of each of the front cutting faces between the 'central body portion and the cutting points being concaved,'the side clearance faces of each of said radially extending cutting portions converging toward the rear edges thereof, said rear edges being curved in a radial direction and extending between the central body portion and each of the cutting points, the front edges of the said side clearance faces meeting with th side edges of the front cutting faces, th said side clearance faces between the central body and the cutting points being concaved and producing a greater cutting clearance as the cutting points wear away.

4. A'multiple bit for cutter chains comprising a solid piece of metal having a central body portion and a plurality of radially disposed spacedapart cutting points with cutting edges extending between said points substantially outlining a triangular contour, the contour of the said cutting edges between the said cutting points and the central body portion being concave, one side of said multiple bit being approximately fiat and the other side being provided with radial ribs extending to said points, each rib having a spacedapart'pair of angularly disposed side clearance faces, one pair individual to each rib, each of said side clearance faces being concaved and producing a greater cutting clearance as the cutting points wear away.

HARRY M. MORROW. 

